|Year : 2023 | Volume
| Issue : 1 | Page : 98-102
A study of dermatophytosis in patients attending dermatology outdoor patient department at a tertiary care center
Vaibhavi Vijay Nanoty1, Priyanka Kishanbhai Patel2, Rajesh Mahadeo Trimukhe3, Milind Ramchandra Ubale1, Debapriya Das Choudhury1, Pradnya R Joshi4
1 Department of Microbiology, Rajiv Gandhi Medical College and CSM Hospital, Thane, Maharashtra, India
2 Department of Microbiology, P.D. Hinduja Hospital, Mumbai, Maharashtra, India
3 Department of Anaesthesiology, Bharatratna Dr. Babasaheb Ambedkar Municipal General Hospital, Mumbai, Maharashtra, India
4 Department of Dermatology, Rajiv Gandhi Medical College and CSM Hospital, Thane, Maharashtra, India
|Date of Submission||09-Mar-2022|
|Date of Acceptance||21-Jun-2022|
|Date of Web Publication||21-Jan-2023|
Dr. Milind Ramchandra Ubale
C703 Shrikrishna Darshan CHS, Near Ridhi Sidhi CHS, Pancharatna Dwar, Devakinandan Bus Stop, Pakhadi, Thane - 400 605, Maharashtra
Source of Support: None, Conflict of Interest: None
BACKGROUND AND PURPOSE: Dermatophytosis is a superficial fungal infection of keratinized tissue caused by dermatophytes. The dermatophytes are included in three fungal genera: Epidermophyton, Microsporum, and Trichophyton. The infections caused by dermatophytes are known as ringworm or tinea infections. Although there are increasing numbers of antifungals available for the treatment of dermatophytes, some cases and relapses have been unresponsive to treatment. The aim and objectives of the present study are to identify the dermatophyte species causing superficial fungal infections and study their susceptibility to antifungals.
MATERIALS AND METHODS: A total of 60 clinically diagnosed cases of dermatophytosis of patients attending the dermatology outdoor patient department were studied. The samples of these patients were collected and processed for microscopic examination and fungal culture. The causative dermatophytes were isolated and identified. Antifungal susceptibility testing of dermatophytes was done by Epsilometer strip minimum inhibitory concentration method against antifungal agents – fluconazole, itraconazole, and terbinafine.
RESULTS: The most common clinical presentation in patients found was tinea corporis. Maximum dermatophyte isolates obtained on culture were Trichophyton rubrum. On antifungal susceptibility testing, terbinafine showed good results compared to azoles.
CONCLUSION: Antifungal susceptibility testing of dermatophytes could be performed to study response and assist clinicians in choosing an effective therapy for patients.
Keywords: Dermatophytes, antifungal, Trichophyton, tinea
|How to cite this article:|
Nanoty VV, Patel PK, Trimukhe RM, Ubale MR, Choudhury DD, Joshi PR. A study of dermatophytosis in patients attending dermatology outdoor patient department at a tertiary care center. Indian J Health Sci Biomed Res 2023;16:98-102
|How to cite this URL:|
Nanoty VV, Patel PK, Trimukhe RM, Ubale MR, Choudhury DD, Joshi PR. A study of dermatophytosis in patients attending dermatology outdoor patient department at a tertiary care center. Indian J Health Sci Biomed Res [serial online] 2023 [cited 2023 Jan 28];16:98-102. Available from: https://www.ijournalhs.org/text.asp?2023/16/1/98/368315
| Introduction|| |
Dermatophytosis is a superficial fungal infection of keratinized tissue caused by dermatophytes. The dermatophytes are included in three fungal genera: Epidermophyton, Microsporum, and Trichophyton. The infections caused by dermatophytes are known as ringworm or tinea infections. The Trichophyton species usually infect the skin, hair, and nails. The Microsporum species infect the skin and hair not the nails. The Epidermophyton species infect the skin as well as nails but not the hair.
A high incidence of intrafamilial tinea infections, misuse of corticosteroid-containing topical antifungal preparations, poor compliance to treatment, and poor personal hygiene are associated with recurrences and poor responses to treatment.
Although an increasing number of antimycotics have become available for the treatment of dermatophytosis, there are reports suggesting resistance of dermatophytes to antimicrobial agents. In the last few years, India has documented an increased record of dermatophyte infection and also found a change in the different clinical presentation, response to drug, and relapsing of infection with same or different fungus. In the present study, dermatophyte species causing dermatophytosis were identified and antifungal susceptibility testing was done by Epsilometer (E) strip method.
| Materials and Methods|| |
The study was carried out at a tertiary health-care center in Central India over a period of 3 months. The institutional ethic committee approval was obtained. A total of 60 patients attending the dermatology outdoor patient department (OPD) and clinically diagnosed with dermatophytosis were included in this cross-sectional study. History of these patients consisting of demographic details, risk factors, family history, symptoms, relapse, and treatment taken was noted. Any patients with secondary bacterial infection of dermatophytic lesion were excluded from the study. Ethical clearance was obtained from Rajiv Gandhi Medical College Institutional Ethical Committee with Ref no: RGMC/ICEC/A/87 dated 14/12/2018,.
Samples were collected from patients who were clinically diagnosed cases of dermatophytosis. After cleaning the infected area with 70% alcohol, samples were collected by scraping the lesion from the center to the edge, crossing the lesion margin with a sterile scalpel blade. Scraping of the skin from the active border of the lesions was collected. In cases of tinea capitis, hair mount was taken, and in onychomycosis, nail clippings were taken.
Microscopic examination was performed with 10% potassium hydroxide (KOH). For nail clipping, the sample was inoculated in 20%–40% KOH in tube and kept overnight. All specimens were inoculated on Sabouraud's dextrose agar medium containing chloramphenicol and cycloheximide and dermatophyte test medium and incubated at 25°C and 37°C for 4 weeks. Any fungal growth was identified based on colony morphology, pigmentation, growth rate, microscopy using lactophenol cotton blue (LPCB) mount, and slide culture.
The dermatophyte isolates were grown on potato dextrose agar and incubated at 30°C for 4–5 days or till sufficient conidiation was present. Suspension with sterile normal saline was made by gently probing the surface of fungal colonies with the tip of a sterile Pasteur pipette. The suspension was allowed to settle for 5–10 min. The conidia were counted with the help of hemocytometer. The inoculum suspensions were prepared and adjusted to 65%–70% transmittance at a wavelength of 530 nm corresponding to a concentration of 105–106 colony-forming unit/ml verified by quantitative plate counts. The synthetic Roswell Park Memorial Institute 1640 medium plates (with glutamine and phenol red without bicarbonate) were inoculated with sterile cotton swab. After excess moisture was absorbed into the agar and the surface was completely dry, an E-test strip was applied to each plate. The plates were incubated at 28°C for 72–96 h.
Determination of minimum inhibitory concentration (MIC) endpoints
In general, MIC was defined as the lowest drug concentration at which the border of the elliptical inhibition zone intercepted the MIC scale on the E-test strip. When a double halo of growth was observed, the MIC was read at the point where growth was completely inhibited. When different intersections were observed on either side of the strip, the highest MIC value was read.
| Results|| |
A total of 60 clinically diagnosed cases of dermatophytosis attending dermatology OPD at a tertiary care hospital were studied. The most common clinical presentation among these patients was tinea corporis (65%), followed by combination of tinea corporis and tinea cruris (10%) Other presentations included tinea cruris (5%), onychomycosis (5%), tinea pedis (5%), tinea manuum and onychomycosis (5%), and tinea capitis (5%).
Of these 60 patients, 75% belonged to rural areas and 25% hailed from urban areas. Males were predominantly infected than females with a ratio of 1.5:1. Majority of the patients belonged to the age group of 21–40 years.
Clinical samples were collected from these patients and processed in the microbiology laboratory. On direct microscopy on KOH mount, fungal elements were detected in 46 (76.67%) samples. On culture, a total of 20 dermatophyte isolates were obtained. The species identification was done by slide culture and LPCB mount. Cultures which showed contamination were not included for further study. Some yeasts detected in few samples were considered to be colonizing the skin. Out of the 20 fungal culture isolates, Trichophyton rubrum was the most common isolate, followed by Trichophyton mentagrophytes, Trichophyton tonsurans, and Trichophyton verrucosum, as shown in [Figure 1].
The antifungal susceptibility testing of these culture isolates was done by agar diffusion method against antifungals – fluconazole, itraconazole, and terbinafine, and MICs were calculated using E-strip.
The in vitro susceptibilities of 20 clinical isolates of dermatophytes to three antifungal agents as determined by E-test are summarized in [Table 1]. The MIC range of terbinafine was 0.002–32 μg/ml, itraconazole – 0.032–32 μg/ml, and fluconazole – 0.016–256 μg/ml.
|Table 1: In vitro susceptibilities of different isolates of dermatophytes|
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The geometric mean of MIC was calculated for isolates of T. rubrum and Trichophyton mentagrophytes. The lowest geometric mean of MIC values was of terbinafine followed by itraconazole as in [Table 2]. In the isolate of Trichophyton tonsurans, the lowest MIC value was of terbinafine, while in the isolate of Trichophyton verrucosum, the lowest MIC value was of itraconazole. The MIC value of fluconazole was highest against all the isolates.
|Table 2: Geometric mean of minimum inhibitory concentration of antifungals for Trichophyton rubrum and Trichophyton mentagrophytes|
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| Discussion|| |
The present study was carried out to study the epidemiological pattern, clinical presentation, dermatophyte species causing superficial fungal infections, and their antifungal susceptibility pattern. The study was carried out at a tertiary health-care center in Central India. A total of 60 clinically suspected cases of superficial fungal infections who visited the dermatology outpatient department were studied. All the age groups and both sexes were included in the study. Maximum patients were in the age group of 21–40 years. More incidence in the youth can be attributed to their outdoor working habits as compared to other age groups. The male-to-female ratio was 1.5:1. Similar results were obtained by Nornoha et al. Male preponderance could be due to the fact that males are more involved in outdoor physical activities, which leads to excessive sweating making a favorable environment for fungal infections. The lower incidence of dermatophytosis in females could be due to the not reporting of the female patients to the hospitals due to prevailing social stigma, especially in the rural population in India. However, a study done by Das et al. showed a higher predominance in female patients.
Hot and humid climate in tropical and subtropical countries like India makes dermatophytosis a very common superficial fungal infection. This study was carried out in Central India where the climate is mostly hot and humid. Factors such as socioeconomic conditions, lifestyle, and migration also play a further significant role in the prevalence of dermatophytosis in the population.
In this study, the most common clinical presentation was tinea corporis (65%), followed by combination of tinea corporis and cruris (10%). These results correlated with the results of Nornoha et al., A. Naglot et al., and Channe et al.,,
The clinical samples of these patients were collected and processed in the microbiology laboratory. Diagnosis of superficial mycosis is based on KOH mount and fungal culture. Identification of fungal isolates till species level is helpful for therapeutic domain. In this study, T. rubrum was the most common isolated species (55%), followed by Trichophyton mentagrophytes (35%), Trichophyton tonsurans (5%), and Trichophyton verrucosum (5%). Similar results were obtained by Indira, Gupta, and Kohli., However, Das et al. found Trichophyton verrucosum as the most common isolate in Northeast India region. While Channe and Tankhiwale reported Trichophyton mentagrophytes as the most common isolate followed by Trichophyton tonsurans in their study in Central India. Pathania et al. reported Trichophyton mentagrophytes as the most common isolate followed by T. rubrum in North India.
To predict the ability of a given antimycotic agent to eradicate dermatophytes and help managing patients, determination of the in vitro antifungal susceptibility of dermatophytes would be helpful in understanding a failed or successful treatment. However, not all species have the same susceptibility pattern and it may be necessary to perform in vitro susceptibility testing for the selection and monitoring of antifungal therapy. Although a reference method is not yet available, various techniques have been used to test dermatophytes, including broth macro- and microdilution methods, agar dilution, and disk diffusion. However, these methods are time-consuming and labor-intensive and are not practical for the clinical laboratory. Therefore, simple alternative approaches are needed. The E-test is a simple, agar-based, quantitative MIC method. It is a new and promising method with broad applications in clinical laboratory practice. However, there are only a few reports describing the use of this method for dermatophytes. In this study, MIC was calculated using E-strip agar diffusion method. MIC values were calculated by the lowest drug concentration at which the border of the elliptical inhibition zone of inhibition intercepted the MIC scale on the E-test strip.
[Table 2] shows the MIC ranges and geometric mean of antifungals against isolates of T. rubrum and Trichophyton mentagrophytes. The lowest geometric mean of MIC values was of terbinafine, followed by itraconazole for isolates of T. rubrum and Trichophyton mentagrophytes. In the isolate of Trichophyton tonsurans, the lowest MIC value was of terbinafine, while in the isolate of Trichophyton verrucosum, the lowest MIC value was of itraconazole. The MIC value of fluconazole was highest against all the isolates.
Terbinafine was the most potent drug followed by ketoconazole in a study conducted by Indira, while in a study carried out by Das et al., itraconazole showed the lowest MIC against antifungals., Pathania et al. found that fluconazole was moderately effective according to the in vitro susceptibility results.
Till now, the breakpoints have not been defined for the dermatophytes due to lack of data on the clinical correlation, pharmacokinetic/pharmacodynamic studies, or epidemiological cutoff MIC values. Hence, experts opine that it is logical not to use the term, “resistant” in the absence of these definitive criteria for dermatophytes. With this background, increase in the MIC values of isolates to antifungals does not imply that there is an absolute resistance; instead, this only warrants the use of adequate or higher dosage of these drugs or a longer duration of treatment to get the clinical response. Hence, there is a need of more research and standardization of antifungal susceptibility testing.
It is likely that dermatophyte organisms are becoming more virulent with a gradual increase in the MIC of commonly used antifungal drugs as a result of various host, environmental, and treatment factors posing a great emerging health hazard to the community.
| Conclusion|| |
Dermatophytosis is a common problem in hot and humid tropical areas. In the present study, the most common clinical type was tinea corporis. Males showed predominance than females. The diagnosis of dermatophytosis is made by the clinical presentations, KOH mount, and culture which aids in the treatment of the disease. The most common isolate was T. rubrum. The antifungal susceptibility testing can be useful for the choice of antifungal treatment for dermatophyte infection and also in cases which are unresponsive to treatment. We found terbinafine could be a better option for the treatment of dermatophytosis unresponsive to treatment. However, there is a need of more research and standardization in the MIC testing of antifungal agents against dermatophytes.
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Conflicts of interest
There are no conflicts of interest.
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